March storms brighten future of winter-run Chinook salmon

Seasonal storms that have raised the region’s reservoir water levels to their highest points in the last two years could bolster this year’s run of Chinook salmon, water and wildlife officials said Wednesday.

The recent drought has hurt the endangered species’ numbers as warmer water was released out of increasingly drier reservoirs. That warmer-than-normal water has killed the Chinook’s eggs after they’ve spawned.

This year’s population, however, is expected to fare better with plenty of colder water waiting to be released inside Shasta Lake reservoir, said Lewis Bair, general manager of Reclamation District 108, a local state agency that handles flood control, drainage and irrigation services to farmers over 75 square miles in Yolo and Colusa counties.

The impact of recent rains became clear at a multipartner announcement Wednesday at Wallace Weir, where officials detailed improvements to the region’s water management system. In attendance were members from the industry group California Trout and the Northern California Water Association as well as rice farmers.

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Among the improvements, state water contractors are planning to spend $8.5 million to build a bladder dam, new road, fish barrier and fish trapping facility at the Wallace Weir so that winter-run Chinook won’t get lost in the Colusa Canal. Instead, the fish will be ushered back to the Sacramento River to reach spawning areas just below Shasta Lake reservoir.

The future is also looking bright for a summer spawn of the species with Shasta reservoir now 300,000 acre-feet above its normal stage for this time of the year. The reservoir now contains 3.8 million acre-feet, compared to the average of 3.5 million acre-feet, Bair said.

Both Shasta Lake and Lake Oroville have reached flood encroachment stage, meaning the storage space reserved for flood protection has been used up. With more rainfall expected this weekend, Bair expects the reservoir will have to release water to relieve the water burden.

That release should prove a boon to winter-run Chinook. “It would be beneficial for the reservoir to spill water out for a short duration at a fairly high flow because that would help clean up the spawning gravel,” which is where the salmon deposit their eggs, Bair said.

At Shasta Lake, the fish will start spawning around April 15, which means any such release would happen before then, Bair said.

The release would first skim off the warmest water at the top of the lake’s water column. “You preserve your coldest water so that you can release that over the summer,” Bair said.

This year’s incoming population of winter-run Chinook is now making its way under the Golden Gate Bridge toward the Delta and headed north to Lake Shasta, said Maria Rea, supervisor with the National Marine Fisheries Service.

Many salmon lose their way after they pass Rio Vista in the Delta, with hundreds of them ending up in the Colusa Canal at Wallace Weir, requiring a costly rescue. “In 2013, it was found there were a lot of winter-run Chinook in the canals of the Glenn-Colusa irrigation district, and they were not able to spawn,” Rea said.

On Wednesday, Rea also detailed a five-year action plan by the agency to help eight endangered species, including winter-run Chinook. That plan will dovetail with other regional infrastructure projects creating smarter water management during times of drought or flood events.

“One of the plans includes fixing the Yolo Bypass at Wallace Weir and continuing water management at Shasta reservoir,” Rea said. “Unfortunately due to drought and low storage at Shasta reservoir, we’ve lost two out of three year classes of winter-run Chinook due to temperature effects.”